Aerosol-assisted chemical vapor

Films at NASA GRC were deposited using homemade spray or aerosol-assisted chemical vapor deposition (AACVD) reactors to exploit the lower deposition temperature enabled by the simpler decomposition chemistry for the SSPs.6 9 AACVD is a simple and inexpensive process that offers the advantage of a uniform, large-area deposition, just like metal organic CVD (MOCVD), while also offering the low-temperature solution reservoir typical of spray pyrolysis methods. 

Jin, M. H. -G Banger, K. K. Harris, J. D. Hepp, A. F. 2005. CuInS2 films deposited by aerosol-assisted chemical vapor deposition using ternary single-source precursors. Mater. Sci. Eng. B 116 395-401. 

Meng G, Song H, Dong Q, and Peng D. Application of novel aerosol-assisted chemical vapor deposition techniques for SOFC thin films. Solid State Ionics 2004 175 29-34. 

AACVD aerosol-assisted chemical vapor deposition... 

Aerosol-assisted chemical vapor deposition is illustrated by work published by Siadati et al. (2004). An aerosol is a vapor suspension of finely divided particles. The particles can be solid, as in smoke, or liquid, as in fog. A toluene solution of Zr(tfac)4, Y(hfac)3, and Ce(tmhd)4, converted to an aerosol, was used to deliver the metal in a carrier gas of O2. The film deposited was CeC>2-doped Y2O3-stabilized zirconia. The ligands used in this work to produce volatile metal compounds are frequently used in chemical vapor deposition. Trifluoroacety-lacetonate (tfac), hexafluoroacetylacetonate (hfac), and tetramethylheptanedionate (tmhd) are all 3-diketonates, and their structures are shown in Figure 3.22. Like the diethyl dithiocarbamates mentioned above, these precursors could potentially be the source of both the metal and the oxygen in the chemically deposited film. However, to ensure that the metal remains at its highest oxidation state and to avoid a film with mixed valencies on the metal, oxygen is used as the carrier gas. 

Conde-Gallardo, A., Guerrero, M., Fragoso, R. and Castillo, N. (2006). Gas-phase diffusion and surface reaction as limiting mechanisms in the aerosol-assisted chemical vapor deposition of Ti02 films from titanium diisopropoxide. J. Mater. Res. 21(12), 3205-3209. 

Palgrave, R. G. and Parkin, I. P. (2006). Aerosol assisted chemical vapor deposition using nanoparticle precursors A route to nanocomposite thin films. J. Am. Chem. Soc. 128(5), 1587-1597. 

The chemical features of tin(IV) alkoxides, such as pre-existing metal-oxygen bonds in molecular units, high volatility and low decomposition temperatures make them attractive precursors for deposihon of Sn02. The heterometallic complex [Sn(dmae)2Cd(acac)2],Figures.1.2, (acac = 2,4-pentanedionato dmae = N,N -dimethylamino-ethanoate) has been decomposed in aerosol-assisted chemical vapor deposition conditions, producing amorphous tin(IV) oxide films with no detectable cadmium. ... 

Crane, I, Warwick, M., Smith, R., Furlan, N. and Binions, R. (2011) The Application of Electric Fields to Aerosol Assisted Chemical Vapor Deposition Reactions. Journal of The Electrochemical Society 158,D62-D67. 

An aerosol-assisted chemical vapor deposition (AACVD) can also be implemented in the intermediate thermal range between processes B and D, provided that suitable solvents and precursors are used (process C according to the classification made by Vigui6 and Spitz). In proper conditions, the solvent vaporizes first, then the precursor vaporizes (or sublimes) and the vapor reaches the substrate to undergo a heterogeneous solid-gas phase decomposition. Thus, whether or not an aerosol-assisted deposition process may be classified as chemical vapor deposition depends on two factors ... 

Wang HB, Meng GY, and Peng DK. Aerosol and plasma assisted chemical vapor deposition process for multi-component oxide La08Sr02MnO3 thin film. Thin Solid Films 2000 368 275-278. 

Nakaso K, Han B, Ahn KH, Choi M, Okuyama K. Synthesis of non-agglomerated nanoparticles by an electrospray assisted chemical vapor deposition (ES-CVD) method. J Aerosol Sci 2003 84 869-78. 

Moseley PT, Norris JOW, Williams DE (1991) Techniques and mechanisms in gas sensing. Adam Hilger, Bristol Nakaso K, Han B, Ahn KH, Choi M, Okuyama K (2003) Synthesis of non-agglomerated nanoparticles by an electrospray assisted chemical vapor deposition (ES-CVD) method. J Aerosol Sci 34 869-881 Narendar Y, Messing GL (1997) Mechanisms of phase separation in gel-based synthesis of multicomponent metal oxides. Catal Today 35 247-268... 

Silver(I) /3-diketonate derivatives have received significant attention due to the ease with which they can be converted to the elemental metal by thermal decomposition techniques such as metal organic chemical vapor deposition (MOCVD).59 The larger cationic radius of silver(I) with respect to copper(I) has caused problems in achieving both good volatility and adequate stability of silver(I) complexes for the use in CVD apparatus. These problems have been overcome with the new techniques such as super critical fluid transport CVD (SFTCVD), aerosol-assisted CVD (AACVD), and spray pyrolysis, where the requirements for volatile precursors are less stringent. 

Aerosol-assisted CVD introduces rapid evaporation of the precursor and short delivery time of vapor precursor to the reaction zone. The small diffusion distance between the reactant and intermediates leads to higher deposition rates at relatively low temperatures. Single precursors are more inclined to be used in AACVD therefore, due to good molecular mixing of precursors, the stoichiometry in the synthesis of multicomponent materials can be well controlled. In addition, AACVD can be preformed in an open atmosphere to produce thin or thick oxide films, hence its cost is low compared to sophisticated vacuum systems. CVD methods have also been modified and developed to deposit solid phase from gaseous precursors on highly porous substrates or inside porous media. The two most used deposition methods are known as electrochemical vapor deposition (EVD) and chemical vapor infiltration (CVI). 

Although sometimes differentiated from spray pyrolysis, aerosol assisted CVD is essentially the same motif. It is, however, typically not conducted in a flame type regime. Nevertheless, frequently, materials are not transported perpendicular to a substrate surface, thereby bypassing one of the crucial elements of chemical vapor deposition - the ability to secure extraordinary step coverage in high aspect ratio materials, due to the non-line-of-sight technique. 

Chemical vapor deposition refers to the formation of a nonvolatile solid material from the reaction of chemical reactants, called precursors, being in vapor phase in the right constituents. A reaction chamber is used for this process, into which the reactant gases are introduced to decompose and react with the substrate to form thin film or powders There are several main classification schemes for chemical vapor deposition processes. These include classification by the pressure (atmospheric, low-pressure, or ultrahigh vacuum), characteristics of the vapor (aerosol or direct liquid injection), or plasma processing type (microwave plasma-assisted deposition, plasma-enhanced deposition, remote plasma-enhanced deposition)... 

CCVD combustion chemical vapor deposition MOCVD mettil-organic-assisted CVD PECVD plasma-enhanced CVD FACVD flame-assisted CVD AACVD aerosol-assisted CVD ESAVD electrostatic-atomization CVD LPCVD low-pressure CVD APCVD atmospheric-pressure CVD PACVD photo-assisted CVD TACVD thermtil-activated CVD EVD electrochemical vapor deposition RTCVD rapid thermal CVD UHVCVD ultrahigh-vacuum CVD ALE atomic-layer epitaxy PICVD pulsed-injection CVD... 

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